Communication satellites enable communication via links that extend over a long range and have wide area coverage, and provide solutions for various applications, including, for example, broadcasting, video transmission, and digital telephony.
Beam hopping techniques have been shown to increase the efficiency of satellite transmission while simultaneously adapting the resources of the satellite to the actual demand of ground terminals. In beam hopping, the satellite transmission time is partitioned between different beams, each illuminating a different respective area (or cell) on the ground. Beam hopping is applicable for various satellite configurations, including, for example, high throughput satellites that support a high number of beams from a single satellite, and low earth orbit (LEO) satellite constellations that support a high number of beams from multiple LEO satellites. Waveforms that support beam hopping have also been specified for use in the Digital Video Broadcasting—Satellite—Second Generation Extensions (DVB-S2X) standard, which provides efficient packetized data transmission, used for example in broadcast television services.
One major drawback in beam hopping is that the downlink signal from the satellite is not a continuous signal, but is in fact rather bursty. In situations in which the downlink hop times are not pre-scheduled but are rather traffic driven, the receiver requires a long preamble—i.e., header—to be able to acquire and synchronize to the signal. This is further exacerbated when the signal is received at very low signal-to-noise ratio (VLSNR), which in the DVB-S2X standard is nominally down to −10 dB. For such receivers, the transmitting satellite typically must use a very low code rate and a high degree of spreading to ensure proper signal acquisition and decoding at the receiver. The low code rate and high spreading reduces the bandwidth of the downlink signal, resulting in low data rate on the downlink.